Current Search: Adaptive (x)
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Title
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Complex-valued adaptive digital signal enhancement for applications in wireless communication systems.
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Creator
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Liu, Ying, Mikhael, Wasfy, Batarseh, Issa, Yang, Thomas, Hunter, Matthew, Haralambous, Michael, Myers, Brent, University of Central Florida
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Abstract / Description
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In recent decades, the wireless communication industry has attracted a great deal of research efforts to satisfy rigorous performance requirements and preserve high spectral efficiency. Along with this trend, I/Q modulation is frequently applied in modern wireless communications to develop high performance and high data rate systems. This has necessitated the need for applying efficient complex-valued signal processing techniques to highly-integrated, multi-standard receiver devices.In this...
Show moreIn recent decades, the wireless communication industry has attracted a great deal of research efforts to satisfy rigorous performance requirements and preserve high spectral efficiency. Along with this trend, I/Q modulation is frequently applied in modern wireless communications to develop high performance and high data rate systems. This has necessitated the need for applying efficient complex-valued signal processing techniques to highly-integrated, multi-standard receiver devices.In this dissertation, novel techniques for complex-valued digital signal enhancement are presented and analyzed for various applications in wireless communications. The first technique is a unified block processing approach to generate the complex-valued conjugate gradient Least Mean Square (LMS) techniques with optimal adaptations. The proposed algorithms exploit the concept of the complex conjugate gradients to find the orthogonal directions for updating the adaptive filter coefficients at each iteration. Along each orthogonal direction, the presented algorithms employ the complex Taylor series expansion to calculate time-varying convergence factors tailored for the adaptive filter coefficients. The performance of the developed technique is tested in the applications of channel estimation, channel equalization, and adaptive array beamforming. Comparing with the state of the art methods, the proposed techniques demonstrate improved performance and exhibit desirable characteristics for practical use.The second complex-valued signal processing technique is a novel Optimal Block Adaptive algorithm based on Circularity, OBA-C. The proposed OBA-C method compensates for a complex imbalanced signal by restoring its circularity. In addition, by utilizing the complex Taylor series expansion, the OBA-C method optimally updates the adaptive filter coefficients at each iteration. This algorithm can be applied to mitigate the frequency-dependent I/Q mismatch effects in analog front-end. Simulation results indicate that comparing with the existing methods, OBA-C exhibits superior convergence speed while maintaining excellent accuracy. The third technique is regarding interference rejection in communication systems. The research on both LMS and Independent Component Analysis (ICA) based techniques continues to receive significant attention in the area of interference cancellation. The performance of the LMS and ICA based approaches is studied for signals with different probabilistic distributions. Our research indicates that the ICA-based approach works better for super-Gaussian signals, while the LMS-based method is preferable for sub-Gaussian signals. Therefore, an appropriate choice of interference suppression algorithms can be made to satisfy the ever-increasing demand for better performance in modern receiver design.
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Date Issued
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2012
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Identifier
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CFE0004572, ucf:49192
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004572
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Title
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Adaptation and Resilience of Extreme Teams: A Qualitative Study Using Historiometric Analysis.
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Creator
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Padgett, Lauren, Burke, Shawn, Jentsch, Florian, Bowers, Clint, University of Central Florida
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Abstract / Description
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The business and academic worlds agree that team resilience and team adaptation are in increasing need of study. This study explores the behavioral processes of team adaptation(-)specifically, those action phase and interpersonal processes mapped by Marks, Mathieu, and Zaccaro (2001) and overlapping with the team adaptation model by Burke, Stagl, Salas, Pierce, and Kendall (2006) and expanded by Rosen et al. (2011). Additionally, the impact of trigger type on adaptive behaviors is explored as...
Show moreThe business and academic worlds agree that team resilience and team adaptation are in increasing need of study. This study explores the behavioral processes of team adaptation(-)specifically, those action phase and interpersonal processes mapped by Marks, Mathieu, and Zaccaro (2001) and overlapping with the team adaptation model by Burke, Stagl, Salas, Pierce, and Kendall (2006) and expanded by Rosen et al. (2011). Additionally, the impact of trigger type on adaptive behaviors is explored as suggested by Maynard and Kennedy (2016). Theseexplorations are conducted within the context of extreme teams, and the primary method used is Crayne and Hunter's (2018) historiometric analysis (HMA). The chosen sources include crewdiaries and new articles detailing the events of the 2014-2015 Volvo Ocean. Critical incidents are pulled from these sources and coded for trigger type as either taskwork- or teamwork-focused,and the adaptive behaviors in response to these triggers are coded in a bottom up, emergent process. The data is reported as rank-ordered frequencies. Results suggest that resilient teamsengage in some of those processes suggested by the Marks et al. (2001) framework(-)coordination, monitoring, communication, and backup(-)as well as other adaptive behavioral processes. Furthermore, taskwork-focused triggers are seen as resulting in more action phase behavioral adaptation processes, though limited data is found to speak to the mechanisms of teamwork-focused triggers. Future research directions are suggested to include examination of teams of various levels of expertise in both taskwork-specific and generalized teamwork skills.
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Date Issued
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2018
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Identifier
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CFE0007162, ucf:52294
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007162
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Title
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ADAPTIVE FEEDBACK IN SIMULATION-BASED TRAINING.
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Creator
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Billings, Deborah, Gilson, Richard, University of Central Florida
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Abstract / Description
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Feedback is essential to guide performance in simulation-based training (SBT) and to refine learning. Generally outcomes improve when feedback is delivered with personalized tutoring that tailors specific guidance and adapts feedback to the learner in a one-to-on environment. Therefore, emulating by automation these adaptive aspects of human tutors in SBT systems should be an effective way to train individuals. This study investigates the efficacy of automating different types of feedback in...
Show moreFeedback is essential to guide performance in simulation-based training (SBT) and to refine learning. Generally outcomes improve when feedback is delivered with personalized tutoring that tailors specific guidance and adapts feedback to the learner in a one-to-on environment. Therefore, emulating by automation these adaptive aspects of human tutors in SBT systems should be an effective way to train individuals. This study investigates the efficacy of automating different types of feedback in a SBT system. These include adaptive bottom-up feedback (i.e., detailed feedback, changing to general as proficiency develops) and adaptive top-down feedback (i.e., general feedback, changing to detailed if performance fails to improve). Other types of non-adaptive feedback were included for performance comparisons as well as to examine the overall cognitive load. To test hypotheses, 130 participants were randomly assigned to five conditions. Two feedback conditions employed adaptive approaches (bottom-up and top-down), two used non-adaptive approaches (constant detailed and constant general), and one functioned as a control group (i.e., only a performance score was given). After preliminary training on the simulator system, participants completed four simulated search and rescue missions (three training missions and one transfer mission). After each training mission, all participants received feedback relative to the condition they were assigned. Overall performance on missions, knowledge post-test scores, and subjective cognitive load were measured and analyzed to determine the effectiveness of the type of feedback. Results indicate that: (1) feedback generally improves performance, confirming prior research; (2) performance for the two adaptive approaches (bottom-up vs. top-down did not differ significantly at the end of training, but the bottom-up group achieved higher performance levels significantly sooner; (3) performance for the bottom-up and constant detailed groups did not differ significantly, although the trend suggests that adaptive bottom-up feedback may yield significant results in further studies. Overall, these results have implications for the implementation of feedback in SBT and beyond for other computer-based training systems.
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Date Issued
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2010
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Identifier
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CFE0003225, ucf:48555
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0003225
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Title
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DETECTION OF THE R-WAVE IN ECG SIGNALS.
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Creator
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Valluri, Sasanka, Weeks, Arthur, University of Central Florida
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Abstract / Description
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This thesis aims at providing a new approach for detecting R-waves in the ECG signal and generating the corresponding R-wave impulses with the delay between the original R-waves and the R-wave impulses being lesser than 100 ms. The algorithm was implemented in Matlab and tested with good results against 90 different ECG recordings from the MIT-BIH database. The Discrete Wavelet Transform (DWT) forms the heart of the algorithm providing a multi-resolution analysis of the ECG signal. The...
Show moreThis thesis aims at providing a new approach for detecting R-waves in the ECG signal and generating the corresponding R-wave impulses with the delay between the original R-waves and the R-wave impulses being lesser than 100 ms. The algorithm was implemented in Matlab and tested with good results against 90 different ECG recordings from the MIT-BIH database. The Discrete Wavelet Transform (DWT) forms the heart of the algorithm providing a multi-resolution analysis of the ECG signal. The wavelet transform decomposes the ECG signal into frequency scales where the ECG characteristic waveforms are indicated by zero crossings. The adaptive threshold algorithms discussed in this thesis search for valid zero crossings which characterize the R-waves and also remove the Preventricular Contractions (PVC's). The adaptive threshold algorithms allow the decision thresholds to adjust for signal quality changes and eliminate the need for manual adjustments when changing from patient to patient. The delay between the R-waves in the original ECG signal and the R-wave impulses obtained from the algorithm was found to be less than 100 ms.
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Date Issued
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2005
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Identifier
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CFE0000498, ucf:46369
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000498
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Title
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DESIGN AND ANALYSIS OF ADAPTIVE AND RECONFIGURABLE ANTENNAS FOR WIRELESS COMMUNICATION.
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Creator
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Ali, Maha Abdelmoneim, Wahid, Parveen, University of Central Florida
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Abstract / Description
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Modern radar and communication systems have experienced a tremendous increase in the number of antennas onboard, on the ground, and in orbital space. This places a burden due to the confined volume and limited weight requirements especially in space applications. The reconfigurable antenna is a promising and exciting new type of antenna, where through the use of appropriate switches the antenna can be structurally reconfigured, to maintain the elements near their resonant dimensions for...
Show moreModern radar and communication systems have experienced a tremendous increase in the number of antennas onboard, on the ground, and in orbital space. This places a burden due to the confined volume and limited weight requirements especially in space applications. The reconfigurable antenna is a promising and exciting new type of antenna, where through the use of appropriate switches the antenna can be structurally reconfigured, to maintain the elements near their resonant dimensions for several frequency bands. This increases the bandwidth of the antenna dramatically, which enables the use of one antenna for several applications. Four novel reconfigurable antenna elements were designed to work at 2.45 GHz and at 5.78 GHz, to cover the transition period when wireless communication will shift to the 5.78 GHz band. The four elements designed are: the reconfigurable Yagi, the reconfigurable corner-fed triangular loop antenna, the reconfigurable center-fed equilateral triangular loop antenna and the reconfigurable rectangular-spiral antenna. None of these antennas have been reported in the literature. Simulation results for all four antennas were obtained using IE3D. Fabrication and measurements for the Yagi antenna was done and the measured results agree with simulations. All four antennas have very good performance with respect to the 3dB beamwidth and directivity. However the reconfigurable rectangular-spiral antenna is the most compact in size among all four antennas. It is (20 mm x 20 mm) in size. At 2.45 GHz it has a 3dB beamwidth of 870 and directivity of 6.47dB. As for the 5.78GHz frequency the 3dB beamwidth is 82.50 and the directivity is 7.16dB. This dissertation also introduces the use of reconfigurable antenna elements in adaptive arrays. An adaptive array that can null interference and direct its main lobe to the desired signal while being reconfigurable to maintain functionality at several frequency bands has the potential to revolutionize wireless communications in the future. Through several examples, at both the design frequencies, it is shown that the reconfigurable and adaptive antenna arrays are successful in nulling noises incident on the array. These examples illustrate how reconfigurable elements and adaptive arrays can be combined very beneficially for use in wireless communication systems.
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Date Issued
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2004
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Identifier
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CFE0000003, ucf:46147
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000003
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Title
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NONLINEAR ADAPTIVE ESTIMATION ANDITS APPLICATION TO SYNCHRONIZATION OF LORENZ SYSTEM.
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Creator
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Jin, Yufang, Qu, Zhihua, University of Central Florida
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Abstract / Description
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Synchronization and estimation of unknown constant parameters forLorenz-type transmitter are studied under the assumption that oneof the three state variables is not transmitted and thattransmitter parameters are not known apriori. An adaptivealgorithm is proposed to estimate both the state and systemparameters. Since Lorenz system shows the property of sensitivityto initial conditions and evolves in different mode with parametervariation, an equivalent system is introduced. The...
Show moreSynchronization and estimation of unknown constant parameters forLorenz-type transmitter are studied under the assumption that oneof the three state variables is not transmitted and thattransmitter parameters are not known apriori. An adaptivealgorithm is proposed to estimate both the state and systemparameters. Since Lorenz system shows the property of sensitivityto initial conditions and evolves in different mode with parametervariation, an equivalent system is introduced. The adaptiveobserver is designed based on this equivalent system without anyrequirement on initial conditions of the observer. It is shown byLyapunov arguments and persistent excitation analysis thatexponential stability of state and parameter estimation isguaranteed. Simulation results are included to demonstrateproperties of the algorithm. In a practical communication system,the received signals presented at the receiver part differ fromthose which were transmitted due to the effects of noise. Theproposed synchronization scheme is robust with regard to externalbounded disturbance. When an additive white gaussian noise (AWGN)channel model is considered, estimates of state and parameterconverge except for small errors. The results show promise ineither coherent detection or the message decoding intelecommunication systems.
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Date Issued
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2004
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Identifier
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CFE0000114, ucf:46187
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000114
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Title
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Lyapunov-Based Control Design for Uncertain MIMO Systems.
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Creator
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Wang, Zhao, Behal, Aman, Boloni, Ladislau, Haralambous, Michael, University of Central Florida
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Abstract / Description
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In this dissertation. we document the progress in the control design for a class of MIMO nonlinear uncertain system from five papers. In the first part, we address the problem of adaptive control design for a class of multi-input multi-output (MIMO)nonlinear systems. A Lypaunov based singularity free control law, which compensates for parametric uncertainty in both the drift vector and the input gain matrix, is proposed under the mild assumption that the signs of the leading minors of...
Show moreIn this dissertation. we document the progress in the control design for a class of MIMO nonlinear uncertain system from five papers. In the first part, we address the problem of adaptive control design for a class of multi-input multi-output (MIMO)nonlinear systems. A Lypaunov based singularity free control law, which compensates for parametric uncertainty in both the drift vector and the input gain matrix, is proposed under the mild assumption that the signs of the leading minors of thecontrol input gain matrix are known. Lyapunov analysis shows global uniform ultimate boundedness (GUUB) result for the tracking error under full state feedback (FSFB). Under the restriction that only the output vector is available for measurement, an output feedback (OFB) controller is designed based on a standard high gain observer (HGO) (-) stability under OFB is fostered by the uniformity of the FSFB solution. Simulation results for both FSFB and OFB controllers demonstrate the ef?cacy of the MIMO control design in the classical 2-DOF robot manipulator model.In the second part, an adaptive feedback control is designed for a class of MIMO nonlinear systems containing parametric uncertainty in both the drift vector and the input gain matrix, which is assumed to be full-rank and non-symmetric in general. Based on an SDU decomposition of the gain matrix, a singularity-free adaptive tracking control law is proposed that is shown to be globally asymptotically stable (GAS) under full-state feedback. Output feedback results are facilitated via the use of a high-gain observer (HGO). Under output feedback control, ultimate boundedness of the error signals is obtained (&)#241; the size of the bound is related to the size of the uncertainty in the parameters. An explicit upper bound is also provided on the size of the HGO gain constant.In third part, a class of aeroelastic systems with an unmodeled nonlinearity and external disturbance is considered. By using leading- and trailing-edge control surface actuations, a full-state feedforward/feedback controller is designed to suppress the aeroelastic vibrations of a nonlinear wing section subject to external disturbance. The full-state feedback control yields a uniformly ultimately bounded result for two-axis vibration suppression. With the restriction that only pitching and plunging displacements are measurable while their rates are not, a high-gain observer is used to modify the full-state feedback control design to an output feedback design. Simulation results demonstrate the ef ? cacy of the multi-input multi-output control toward suppressing aeroelastic vibration and limit cycle oscillations occurring in pre and post? utter velocity regimes when the system is subjected to a variety of external disturbance signals. Comparisons are drawn with a previously designed adaptive multi-input multi-output controller.In the fourth part, a continuous robust feedback control is designed for a class of high-order multi-input multi-output (MIMO) nonlinear systems with two degrees of freedom containing unstructured nonlinear uncertainties in the drift vector and parametric uncertainties in the high frequency gain matrix, which is allowed to be non-symmetric in general. Given some mild assumptions on the system model, a singularity-free continuous robust tracking control law is designed that is shown to be semi-globally asymptotically stable under full-state feedback through a Lyapunov stability analysis. The performance of the proposed algorithm have been verified on a two-link robot manipulator model and 2-DOF aeroelastic model.
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Date Issued
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2012
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Identifier
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CFE0004345, ucf:49420
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004345
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Title
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STABILIZATION AND TRACKING OF THE VAN DER POL OSCILLATOR.
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Creator
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Zhao, Xin, Haralambous, Michael, University of Central Florida
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Abstract / Description
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In this thesis, the stabilization and tracking problem of the Van der Pol oscillator is studied by using advanced control techniques. First, the linear state feedback and linear adaptive state feedback controllers for the stabilization problem are designed. Then, non-linear state feedback and output feedback controllers are proposed for the tracking problem with known parameters. Finally, a dynamic output feedback controller based on adaptive backstepping technique is introduced for the...
Show moreIn this thesis, the stabilization and tracking problem of the Van der Pol oscillator is studied by using advanced control techniques. First, the linear state feedback and linear adaptive state feedback controllers for the stabilization problem are designed. Then, non-linear state feedback and output feedback controllers are proposed for the tracking problem with known parameters. Finally, a dynamic output feedback controller based on adaptive backstepping technique is introduced for the tracking problem when all parameters of the Van der Pol system are unknown.
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Date Issued
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2005
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Identifier
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CFE0000569, ucf:46444
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000569
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Title
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Human Factor Effects of Simulating Battlefield Malodors in Field Training.
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Creator
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Pike, William, Proctor, Michael, Shumaker, Randall, Sims, Valerie, Ness, James, Burgess, Deborah, University of Central Florida
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Abstract / Description
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In order to explore how to better utilize simulated odors for live training, a study of 180 United States Military Academy at West Point cadets was undertaken to determine whether pre-exposure to a simulated malodor may result in an amelioration of performance issues, as well as improving performance of a complex task. Exposure to malodors has long been shown to increase stress and escape behavior, and reduce performance of complex tasks, in addition to degrading other human factor areas....
Show moreIn order to explore how to better utilize simulated odors for live training, a study of 180 United States Military Academy at West Point cadets was undertaken to determine whether pre-exposure to a simulated malodor may result in an amelioration of performance issues, as well as improving performance of a complex task. Exposure to malodors has long been shown to increase stress and escape behavior, and reduce performance of complex tasks, in addition to degrading other human factor areas. However, desensitization to a particular odor through a process known as olfactory adaptation, could ameliorate these performance issues. In this study, cadets were assigned to one of three conditions: Adaptation (odor/odor, to denote presence or absence of the simulated malodor in each of two phases), No Adaptation (no odor/odor), or Control (no odor/no odor). Participants wore a device to track electrodermal activity, a predictor of stress. Participants spent 12 minutes in a tent taking a quiz involving a common military task. After two minutes, a scent delivery system was turned on, delivering either the simulated malodor (burnt human flesh) or no odor. Participants exited the tent after the full 12 minutes and rated the air quality of the tent. They repeated the exercise in a second tent, with a similar quiz. Metrics of interest included perceived intensity and detection time, common metrics for gauging olfactory adaption, as well as electrodermal activity, escape behavior, and task performance. Results indicate participants in the Adaptation condition were partially desensitized to the malodor. Performance metrics did not show any statistical significance for stress, escape behavior, or performance improvement for the Adaptation condition, although there was a strong negative correlation of performance and perceived mental demand. Performance improvement and stress results were trending in the expected directions. This study differed from previous work in olfactory adaptation studies by linking adaptation to performance during a relevant complex task, and provides valuable lessons for future olfactory studies. From a more applied viewpoint, this study also provides insight for future research into the incorporation of malodors in live training.
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Date Issued
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2018
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Identifier
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CFE0007357, ucf:52097
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007357
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Title
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Mathematical Foundations of Adaptive Quantum Processing.
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Creator
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Bonior, Daniel, Mucciolo, Eduardo, Martin, Keye, Argenti, Luca, Shivamoggi, Bhimsen, Marinescu, Dan, University of Central Florida
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Abstract / Description
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Quantum information has the potential to revolutionize the way we store, process, transfer and acquire information [1,14,15,21,37]. In particular, quantum information offers exciting new approaches to secure communication, computation and sensing. However, in order to realize such technologies, we must first understand the effect that environmental noise has on a quantum system. This dissertation builds upon recent studies that have explored the underlying structure of quantum information and...
Show moreQuantum information has the potential to revolutionize the way we store, process, transfer and acquire information [1,14,15,21,37]. In particular, quantum information offers exciting new approaches to secure communication, computation and sensing. However, in order to realize such technologies, we must first understand the effect that environmental noise has on a quantum system. This dissertation builds upon recent studies that have explored the underlying structure of quantum information and the effects of qubit channels in quantum communication protocols.This work is divided into five main chapters, with Chapter 1 being a brief introduction to quantum information. We then begin Chapter 2 by defining the error function for our qubit communication protocols. From there we explore the properties of our error functions and the topological space that they form. In Chapter 3 we consider the newly patented process Adaptive Quantum Information Processing, patent number US9838141 B2; originally outlined by Martin in [23]. We restate the adaptive scheme and exemplify its application through the Prepare and Send Protocol and Quantum Key Distribution. Applying our results from Chapter 2, we obtain an expression for the adaptability of unital channels in these two protocols and classify the channels that admit the most improvement. We dedicate Chapter 4 to the derivation of gravitational noise, and show that in certain circumstances gravity results in a channel that can be maximally improved in Adaptive QKD [3,14,16]. Lastly, we study the set of error functions through the lens of domain theory. Domain theory is a subset of mathematics that was developed in order to rigorously formalize computations. The first four chapters are all consequences of past discoveries in the mathematical structure of quantum channels. In Chapter 5 we characterize the set of error functions through domain theory, extending the mathematical foundations of quantum information. [12,18,20, 22, 23,25].
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Date Issued
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2018
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Identifier
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CFE0007313, ucf:52124
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007313
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Title
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ON THE USE OF GAUSSIAN FILTER FUNCTIONS FOR ADAPTIVE OPTICS.
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Creator
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Assad, Merfit, Andrews, Larry, University of Central Florida
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Abstract / Description
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For adaptive optic systems, the use of aperture filter functions calculated using various Zernike modes can be useful in removing lower-order aberrations caused by atmospheric turbulence. Traditionally, these filter functions are calculated using the step function depicting a hard aperture that introduces integrals that are sometimes difficult to integrate and must be done numerically. The Gaussian method can be used in place of the conventional method for calculating the aperture filter...
Show moreFor adaptive optic systems, the use of aperture filter functions calculated using various Zernike modes can be useful in removing lower-order aberrations caused by atmospheric turbulence. Traditionally, these filter functions are calculated using the step function depicting a hard aperture that introduces integrals that are sometimes difficult to integrate and must be done numerically. The Gaussian method can be used in place of the conventional method for calculating the aperture filter functions. Evaluation of the Gaussian approximation for modeling a finite receiver aperture can be made by comparison of reduction in phase variance with results achieved using the conventional method. The validity of Gaussian approximation in this application is demonstrated by the consistency of results between the two methodologies. Comparison of reduction in scintillation by the two methodologies reveals several benefits derived from utilization of Gaussian approximation. The Gaussian approximation produces data that can be interpreted analytically. It further produces greater scintillation reduction. This paper will first examine the use of statistical models for predicting atmospheric turbulence and then the use of Zernike polynomials in adaptive optics. Next, this paper compares the reduction of phase variance and scintillation using the conventional method with the Gaussian approximation to evaluate the effectiveness of the new filter functions. The results of these comparisons are presented both as mathematical expressions and graphically.
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Date Issued
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2006
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Identifier
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CFE0001436, ucf:52885
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001436
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Title
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A quasi-experiment on the degree to which i-Ready Reading Instruction predicted Florida state assessment scores for low performing students compared to students on grade level.
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Creator
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Pierce, Ashley, Sivo, Stephen, Bai, Haiyan, Clark, M. H., Hopp, Carolyn, University of Central Florida
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Abstract / Description
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The purpose of this study was to determine the degree to which i-Ready(&)#174; Reading Instruction (a computer adaptive testing program) predicted Florida Standards Assessment English Language Arts (FSA ELA) scores for low performing students (Level 1) compared to those who are on grade level (Level 3). Participants included students in seventh grade at a central Florida school district who participated in i-Ready(&)#174; Reading Instruction and who had previously scored a Level 1 or Level 3...
Show moreThe purpose of this study was to determine the degree to which i-Ready(&)#174; Reading Instruction (a computer adaptive testing program) predicted Florida Standards Assessment English Language Arts (FSA ELA) scores for low performing students (Level 1) compared to those who are on grade level (Level 3). Participants included students in seventh grade at a central Florida school district who participated in i-Ready(&)#174; Reading Instruction and who had previously scored a Level 1 or Level 3 on the FSA ELA. A hierarchical multiple regression was run to determine the impact of the interaction effect between prior year FSA performance level and time spent in i-Ready(&)#174; Reading Instruction, while controlling for teacher-level and other student-level variables. Regression analyses indicated that prior year FSA ELA performance level did not moderate the degree to which time spent in i-Ready(&)#174; Reading Instruction predicted FSA ELA score gains. Additionally, when the interaction term was removed from the regression, time spent in i-Ready(&)#174; Reading Instruction did not predict FSA ELA score gains.
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Date Issued
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2018
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Identifier
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CFE0007234, ucf:52242
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007234
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Title
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The Self-described Experience of Coping and Adaptation Associated with Workplace Stress of Registered Nurses in the Acute Care Setting in Florida: An Ethnographic Study.
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Creator
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Burr, Joyce, Bushy, Angeline, Sole, Mary, Andrews, Diane, Malvey, Donna, University of Central Florida
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Abstract / Description
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ABSTRACTLittle is known about how nurses learn and use coping and adaptation skills in the workplace. Quantitative studies have identified the factors, nature, and outcomes of nursing stress. However, qualitative studies describing the human experience associated with workplace stress are lacking. The phenomenon of interest for this study using focused ethnographic method is the self-described experience of coping and adaptation associated with workplace stress of registered nurses working 12...
Show moreABSTRACTLittle is known about how nurses learn and use coping and adaptation skills in the workplace. Quantitative studies have identified the factors, nature, and outcomes of nursing stress. However, qualitative studies describing the human experience associated with workplace stress are lacking. The phenomenon of interest for this study using focused ethnographic method is the self-described experience of coping and adaptation associated with workplace stress of registered nurses working 12-hour shifts employed in acute care hospital facilities in east central and central Florida. Three aspects of the phenomena were examined: the self-described experiences of stress, the manner in which coping skills are acquired, and the manner in which adaptation strategies are developed by experienced bedside nursing working 12-hour shifts in acute care hospital facilities. The purposive sample included nine female bedside nurses with five or more years' experience, working 12 hour shifts in acute care hospital facilities on bedside units, with patient ratios of 4:1 or greater. Data were collected using semi-structured, digitally recorded interviews at mutually convenient locations. The qualitative data were analyzed using inductive, constant, comparative process of coding, sorting, generalizing, and memoing to guide exploration and identify emergent themes and patterns. The predominant theme of stress emerged as the overwhelming sense of duty to the patient. Additional themes of coping and adaptation were noted. Recommendations for research, education, practice and policy are offered to support a healthy and sustainable nursing workforce.
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Date Issued
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2012
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Identifier
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CFE0004525, ucf:49280
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004525
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Title
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Facilitating Adaptive Team Performance: The Influence of Membership Fluidity on Learning.
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Creator
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Bedwell, Wendy, Salas, Eduardo, Jentsch, Kimberly, Jentsch, Florian, Rico Munoz, Ramon, Fiore, Stephen, University of Central Florida
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Abstract / Description
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Organizations across work domains that utilize teams to achieve organizational outcomes experience change. Resources change. Project deadlines change. Personnel change. Within the scientific community, research has recently surged on the topic of team adaptation to address the issue of change specifically within teams. There have generally been two lines of research regarding team adaptation (task and membership). This effort is focused on membership. Teams are not static(-)members come and...
Show moreOrganizations across work domains that utilize teams to achieve organizational outcomes experience change. Resources change. Project deadlines change. Personnel change. Within the scientific community, research has recently surged on the topic of team adaptation to address the issue of change specifically within teams. There have generally been two lines of research regarding team adaptation (task and membership). This effort is focused on membership. Teams are not static(-)members come and go. The membership adaptation literature has traditionally focused on the performance effects of newcomers to teams. Yet in practice, more and more teams today experience membership loss without replacement. Military units are stretched to capacity. Economic conditions have forced organizations to do more with less. When members leave, they are rarely, if ever, replaced. The very nature of some organizations lends itself to fluid team memberships. Consider an emergency room where a team of nurses and doctors work on Patient A. When a more critical Patient B arrives that requires the expertise of one of those team members, that doctor will leave the Patient A to tend to the Patient B. This practice is common in such work environments. Yet despite the prevalence of this practice, the scientific community knows very little about the impact of losing members on team performance. The current study examines the impact of membership fluidity on team performance. The purpose of this study was twofold. First, there was the need to address an empirical gap in the adaptation literature by focusing on membership changes (loss and loss with replacement) in non-creative tasks. Second was the consideration of the processes underlying adaptation(-)namely learning, operationalized as the development of effective shared mental models (SMMs). Thus, a primary goal was to determine the magnitude of team performance decrements associated with such changes within a decision-making task as well as the associated changes in team process. Results suggest that three-person intact teams demonstrated greater adaptive performance than membership loss with replacement teams. Furthermore, two-person intact teams developed more similar task and team interaction SMMs than membership loss teams when SMMs were indexed as a Euclidean distance score. There were no differences in the level of sharedness regarding task, team interaction or teammate SMMs for three-person intact teams as compared to membership loss with replacement teams. However, when teammate SMMs were operationalized as the personality facets (i.e., the Big 5) in exploratory analyses, three-person intact teams did develop more similar SMMs regarding the agreeableness facet than membership loss with replacement teams. Additionally, when operationalized as Euclidean distance, the agreeableness facet significantly predicted adaptive team performance(-)specifically, the smaller the distance (i.e., more similar the MMs), the greater the adaptive performance in teams. When operationalized as the similarity index, the neuroticism facet significantly predicted adaptive team performance such that the more similar the SMMs, the greater the adaptive performance in teams. Results suggest that membership fluidity does negatively influence the development of shared mental models among teammates. Furthermore, this study provides additional evidence that teammate and team interaction mental models, which are typically not examined together in team studies, are differentially influenced by membership fluidity and differentially predict outcomes like adaptive team performance. This suggests researchers should include both of these cognitive components of team performance to fully understand the nature of these constructs.
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Date Issued
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2012
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Identifier
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CFE0004356, ucf:49448
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004356
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Title
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Automatic Scenario Generation using Procedural Modeling Techniques.
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Creator
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Martin, Glenn, Hughes, Charles, Moshell, Jack, Fiore, Stephen, Orooji, Ali, University of Central Florida
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Abstract / Description
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Training typically begins with a pre-existing scenario. The training exercise is performed and then an after action review is sometimes held. This (")training pipeline(") is repeated for each scenario that will be used that day. This approach is used routinely and often effectively, yet it has a number of aspects that can result in poor training. In particular, this process commonly has two associated events that are undesirable. First, scenarios are re-used over and over, which can reduce...
Show moreTraining typically begins with a pre-existing scenario. The training exercise is performed and then an after action review is sometimes held. This (")training pipeline(") is repeated for each scenario that will be used that day. This approach is used routinely and often effectively, yet it has a number of aspects that can result in poor training. In particular, this process commonly has two associated events that are undesirable. First, scenarios are re-used over and over, which can reduce their effectiveness in training. Second, additional responsibility is placed on the individual training facilitator in that the trainer must now track performance improvements between scenarios. Taking both together can result in a multiplicative degradation in effectiveness. Within any simulation training exercise, a scenario definition is the starting point. While these are, unfortunately, re-used and over-used, they can, in fact, be generated from scratch each time. Typically, scenarios include the entire configuration for the simulators such as entities used, time of day, weather effects, entity starting locations and, where applicable, munitions effects. In addition, a background story (exercise briefing) is given to the trainees. The leader often then develops a mission plan that is shared with the trainee group. Given all of these issues, scientists began to explore more purposeful, targeted training. Rather than an ad-hoc creation of a simulation experience, there was an increased focus on the content of the experience and its effects on training. Previous work in scenario generation, interactive storytelling and computational approaches, while providing a good foundation, fall short on addressing the need for adaptive, automatic scenario generation. This dissertation addresses this need by building up a conceptual model to represent scenarios, mapping that conceptual model to a computational model, and then applying a newer procedural modeling technique, known as Functional L-systems, to create scenarios given a training objective, scenario complexity level desired, and sets of baseline and vignette scenario facets.A software package, known as PYTHAGORAS, was built and is presented that incorporates all these contributions into an actual tool for creating scenarios (both manual and automatic approaches are included). This package is then evaluated by subject matter experts in a scenario-based (")Turing Test(") of sorts where both system-generated scenarios and human-generated scenarios are evaluated by independent reviewers. The results are presented from various angles.Finally, a review of how such a tool can affect the training pipeline is included. In addition, a number of areas into which scenario generation can be expanded are reviewed. These focus on additional elements of both the training environment (e.g., buildings, interiors, etc.) and the training process (e.g., scenario write-ups, etc.).
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Date Issued
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2012
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Identifier
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CFE0004265, ucf:49525
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004265
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Title
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Tourist responses to potential climate change impacts and adaptation measures in Florida's coastal destinations.
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Creator
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Atzori, Roberta, Fyall, Alan, Fjelstul, Jill, Tasci, Asli, Miller, Graham, University of Central Florida
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Abstract / Description
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Some of the most vulnerable areas across the world have started experiencing the consequences of climate change, with action to deal with it long overdue. Florida, one of the most visited tourist destinations in the world, holds one of the most 'unenviable' positions in terms of its vulnerability to climate change with the effects already visible, particularly on its coastal areas. Climate is one of the major factors in affecting travel motivations and destination choice, and as such the...
Show moreSome of the most vulnerable areas across the world have started experiencing the consequences of climate change, with action to deal with it long overdue. Florida, one of the most visited tourist destinations in the world, holds one of the most 'unenviable' positions in terms of its vulnerability to climate change with the effects already visible, particularly on its coastal areas. Climate is one of the major factors in affecting travel motivations and destination choice, and as such the implications of climate change for tourist behavior and demand patterns are significant. Beside the physical impacts of climate change, society's perception of climate change, and the response to it at various decision-making levels, have become critical issues.This dissertation presents the perspective of tourists who have previously visited Florida, in a hypothetical scenario of changed climatic conditions. It is proposed that existing social representations about climate change, and therefore individuals' attitudes, views and beliefs concerning this phenomenon, need to be taken into account when examining tourists' stated intentions regarding their prospective visitation intentions and potential changes in future tourism demand. Using social representation theory as a theory of reference, this dissertation presents an analysis of visitors' responses to climate change impacts and adaptation measures, in consideration of their attitudes towards climate change. The main purpose of the study was to understand whether, with the implementation of adaptation strategies directed to limit negative impacts of climate change, the likelihood of tourists to return to Florida would improve in comparison with a future in which no action is taken at the state level to address climate change. In this scenario, the filter of social representations in shaping tourists' perspectives was used as a system of explanation of different tourist responses.This study contributes to the tourism and climate change body of knowledge by advancing a further step toward understanding potential responses of tourists in a scenario in which a destination's most appealing climatic and natural resources are impacted by climate change. The existence of a relationship between tourist's visitation intentions and the social representations they hold with respect to climate change offers a different way to look at tourists' stated responses. In fact, this study shows that predicting shifts in tourism demand based on stated visitation intentions requires caution. The findings of this study can encourage future researchers to pursue a more critical way of exploring the meaning behind tourists' stated responses, which could lead to expanding our current understanding of how climate change will transform tourism demand across different destinations.
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Date Issued
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2016
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Identifier
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CFE0006438, ucf:51477
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0006438
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Title
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The Hammer or the Anvil: Developing Operational Adaptability through Simulations at the Tactical Level.
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Creator
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Mccarthy, Michael, Kincaid, John, Smith, Peter, Maxwell, Douglas, University of Central Florida
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Abstract / Description
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Operational Adaptability is a vital characteristic identified by senior Army leaders in today's military force. The U.S. Army is struggling with the definition and training of operational adaptability at the tactical level. In order to be a critical enhancement to the operational mission, operational adaptability needs to be trained through a training model that supports current U.S. Army doctrine. To develop a base foundation of operational adaptability, Soldiers must train as a collective...
Show moreOperational Adaptability is a vital characteristic identified by senior Army leaders in today's military force. The U.S. Army is struggling with the definition and training of operational adaptability at the tactical level. In order to be a critical enhancement to the operational mission, operational adaptability needs to be trained through a training model that supports current U.S. Army doctrine. To develop a base foundation of operational adaptability, Soldiers must train as a collective unit in a simulated operational environment in order to apply characteristics of operational adaptability.
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Date Issued
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2016
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Identifier
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CFE0006536, ucf:51353
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0006536
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Title
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Optical Fluid-based Photonic and Display Devices.
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Creator
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Xu, Su, Wu, Shintson, Li, Guifang, Moharam, M., Wu, Xinzhang, University of Central Florida
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Abstract / Description
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Conventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for...
Show moreConventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for new applications, such as image and signal processing, optical communication, sensing, and lab-on-a-chip, etc. Different operation principles of optical fluid-based photonic devices have been proposed, for instance fluidic pressure, electrochemistry, thermal effect, environmentally adaptive hydrogel, electro-wetting and dielectrophoresis. In this dissertation, several novel optical fluid-based photonic and display devices are demonstrated. Their working principles are described and electro-optic properties investigated.The first part involves photonic devices based on fluidic pressure. Here, we present a membrane-encapsulated liquid lens actuated by a photo-activated polymer. This approach paves a way to achieve non-mechanical driving and easy integration with other photonic devices. Next, we develop a mechanical-wetting lens for visible and short-wavelength infrared applications. Such a device concept can be extended to longer wavelength if proper liquids are employed.In the second part, we reveal some new photonic and display devices based on dielectrophoretic effects. We conceive a dielectric liquid microlens with well-shaped electrode for fixing the droplet position and lowering the operating voltage. To widen the dynamic range, we demonstrate an approach to enable focus tuning from negative to positive or vice versa in a single dielectric lens without any moving part. The possibility of fabricating microlens arrays with different aperture and density using a simple method is also proposed. Furthermore, the fundamental electro-optic characteristics of dielectric liquid droplets are studied from the aspects of operating voltage, frequency and droplet size. In addition to dielectric liquid lenses, we also demonstrate some new optical switches based on dielectrophoretic effect, e.g., optical switch based on voltage-stretchable liquid crystal droplet, variable aperture or position-shifting droplet. These devices work well in the visible and near infrared spectral ranges. We also extend this approach to display and show a polarizer-free and color filter-free display. Simple fabrication, low power consumption, polarization independence, relatively low operating voltage as well as reasonably fast switching time are their key features.
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Date Issued
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2012
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Identifier
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CFE0004620, ucf:49943
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004620
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Title
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DESIGN OF AN ADAPTIVE AUTOPILOT FOR AN EXPENDABLE LAUNCH VEHICLE.
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Creator
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Plaisted, Clinton, Leonessa, Alexander, University of Central Florida
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Abstract / Description
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This study investigates the use of a Model Reference Adaptive Control (MRAC) direct approach to solve the attitude control problem of an Expendable Launch Vehicle (ELV) during its boost phase of flight. The adaptive autopilot design is based on Lyapunov Stability Theory and provides a useful means for controlling the ELV in the presence of environmental and dynamical uncertainties. Several different basis functions are employed to approximate the nonlinear parametric uncertainties in the...
Show moreThis study investigates the use of a Model Reference Adaptive Control (MRAC) direct approach to solve the attitude control problem of an Expendable Launch Vehicle (ELV) during its boost phase of flight. The adaptive autopilot design is based on Lyapunov Stability Theory and provides a useful means for controlling the ELV in the presence of environmental and dynamical uncertainties. Several different basis functions are employed to approximate the nonlinear parametric uncertainties in the system dynamics. The control system is designed so that the desire dresponse to a reference model would be tracked by the closed-loop system. The reference model is obtained via the feedback linearization technique applied to the nonlinear ELV dynamics. The adaptive control method is then applied to a representative ELV longitudinal motion, specifically the 6th flight of Atlas-Centaur launch vehicle (AC-6) in 1965. The simulation results presented are compared to that of the actual AC-6 post-flight trajectory reconstruction. Recommendations are made for modification and future applications of the method for several other ELV dynamics issues, such as control saturation, engine inertia, flexible body dynamics, and sloshing of liquid fuels.
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Date Issued
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2008
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Identifier
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CFE0002006, ucf:47616
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002006
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Title
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RESPONSES OF SMALL RODENTS TO RESTORATION AND MANAGEMENT TECHNIQUES OF FLORIDA SCRUB AT CAPE CANAVERAL AIR FORCE STATION, FLORIDA.
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Creator
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Suazo, Alexis, Stout, I. Jack, University of Central Florida
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Abstract / Description
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Proper habitat management is essential for the survival and reproduction of species, especially those listed under state or federal laws as endangered, threatened or of special concern, and those with small local populations. Land managers use a combination of mechanical cutting and prescribed burning to manage and restore degraded scrub habitat in east central Florida. This approach improves habitat for the endangered Florida scrub-jay (Aphelocoma coerulescens), but little is known about its...
Show moreProper habitat management is essential for the survival and reproduction of species, especially those listed under state or federal laws as endangered, threatened or of special concern, and those with small local populations. Land managers use a combination of mechanical cutting and prescribed burning to manage and restore degraded scrub habitat in east central Florida. This approach improves habitat for the endangered Florida scrub-jay (Aphelocoma coerulescens), but little is known about its effects on other taxa, especially the threatened southeastern beach mouse (Peromyscus polionotus niveiventris). This single species approach may not be beneficial to other taxa, and mechanical cutting and prescribed burning may have detrimental effects on P. p. niveiventris. To evaluate the effects of land management techniques on P. p. niveiventris, I live trapped populations at Cape Canaveral Air Force Station near Titusville, Florida during 2004-2005. I evaluated the relative abundance and related demographic parameters of small mammal populations trapped in compartments under different land management treatments, and investigated the relationship between Florida scrub-jay breeding groups using these compartments and abundance of southeastern beach mice. My results suggest that P. p. niveiventris responded positively to prescribed burning, while the cotton mouse (P. gossypinus) responded positively to the mechanical cutting. Reproduction and body mass of southeastern beach mice were similar across land management compartments. Abundance of Florida scrub-jay breeding groups and southeastern beach mice were positively correlated suggesting that both listed species benefited from the same land management activities. A mosaic of burned and cut patches should be maintained to support small mammal diversity. In addition, adaptive management should be used at CCAFS to understand how small mammals, particularly the southeastern beach mouse, respond to land management activities.
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Date Issued
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2007
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Identifier
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CFE0001521, ucf:47124
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001521
Pages